The present invention relates to a hydrogenation catalyst of carbon monoxide and a method of manufacturing a hydrogenation product primarily containing gasoline fuel oil and diesel fuel oil.
Fuel oil manufactured from a gas mixture (synthetic gas) of carbon monoxide and hydrogen does not contain sulfur which forms sulfur oxide and aromatic hydrocarbon (aromatic) which generates soot and is carcinogenic, unlike fuel oil refined from petroleum. Hence, this type of fuel oil is attracting attention as low-environmental-load, high-quality fuel replacing petroleum fuel.
A hydrogenation product containing the above fuel oil component is conventionally manufactured by reacting the synthetic gas described above at a predetermined temperature and a predetermined pressure in the presence of a catalyst which is formed by causing silica or alumina to carry cobalt or iron. However, this method is not necessarily satisfactory in the manufacture of target components (e.g., gasoline fuel oil components or diesel fuel oil components) at higher selectivity than other components (e.g., methane).
It is an object of the present invention to provide a hydrogenation catalyst of carbon monoxide, which is suited to the manufacture of a hydrogenation product containing target components (e.g., gasoline fuel oil components or diesel fuel oil components) at high selectivity from a gas mixture of hydrogen and carbon monoxide.
It is another object of the present invention to provide a method of manufacturing a hydrogenation product, capable of manufacturing a hydrogenation product containing target components (e.g., gasoline fuel oil components or diesel fuel oil components) at high selectivity from a gas mixture of hydrogen and carbon monoxide.
According to the present invention, there is provided a hydrogenation catalyst of carbon monoxide, comprising a transition metal and a porous material carrying the transition metal, the porous material having pores, 90% or more of which are fine pores each having a diameter of 1 to 50 nm.
According to the present invention, there is provided a method of manufacturing a hydrogenation product, comprising reacting a gas mixture containing carbon monoxide and hydrogen at a temperature of 200 to 400xc2x0 C. and a pressure of 0.1 to 10 MPa in the presence of a catalyst in which a transition metal is carried by a porous material in which 90% or more of all pores are fine pores each having a diameter of 1 to 50 nm.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
The present invention will be described in detail below.
A hydrogenation catalyst of carbon monoxide according to the present invention has a structure in which a transition metal or a noble metal is carried by a porous material in which 90% or more of all pores are fine pores each having a diameter of 1 to 50 nm.
This porous material is made of pure silica or a material formed by introducing a metal such as aluminum or gallium to pure silica as a base.
The xe2x80x9cpore diameterxe2x80x9d is the peak top of the distribution of pore diameters measured.
By defining the dimensions of fine pores and the fine pore distribution of the porous material within the above ranges, the transition metal can be carried as it is kept fine and uniformly dispersed. It is preferable that 90% or more of all pores in the porous material are fine pores each having a diameter of 1 to 10 nm. Known examples of this silica porous material include MCM-41 developed by Mobil Oil, FSM-16 developed by Tokyo University and Toyota Central Laboratory, and SBA-15 developed by Stanford University. MCM-41 is manufactured, for example, by hydrothermally synthesizing sodium silicate and hexadecyltrimethylammoniumbromide as a silica source and a surfactant (template), respectively, at 120xc2x0 C. in a pressure reaction vessel (autoclave).
As the transition metal, it is possible to use cobalt, nickel, iron, copper, chromium, manganese, zirconium, molybdenum, tungsten, rhenium, osmium, iridium, palladium. silver, ruthenium, rhodium, gold, and platinum. Cobalt, iron, ruthenium, rhodium, and platinum arc particularly preferable.
When the transition metal is cobalt or iron, this transition metal is preferably loaded within the range of 5 to 40 wt % by the porous material. When the transition metal is a noble metal selected from ruthenium, rhodium, and platinum, this transition metal is preferably loaded within the range of 1 to 15 wt % by the porous material. If the loaded amount of the transition metal is less than the lower-limit value of the above range, during the reaction of a gas mixture of hydrogen and carbon monoxide the conversion (to be described later) of carbon monoxide may decrease. On the other hand, if the loaded amount of the transition metal exceeds the upper-limit value of the above range, the conversion of carbon monoxide corresponding to this loaded amount cannot be expected.
The aforesaid hydrogenation catalyst of carbon monoxide is manufactured by, e.g., the IMP method or the TIE method described below.
(IMP method)
First, a porous material such as MCM-41 is air-calcined to remove any residual surfactant (template) by burning at a temperature of 500 to 600xc2x0 C. Subsequently, the calcined porous material is dipped into an aqueous solution of a transition metal compound and impregnated with this aqueous solution. After that, the porous material is again dried and calcined at a temperature of 500 to 600xc2x0 C. to manufacture a target catalyst.
(TIE method)
First, a porous material such as uncalcined MCM-41 is added to an aqueous solution of a transition metal compound, and the porous material and the aqueous solution are mixed. Since some surfactant (template) remains in the porous material, transition metal ions and template ions are exchanged. Subsequently, the mixture is dried and calcined at a temperature of 500 to 600xc2x0 C. to remove the template by burning, thereby manufacturing a target catalyst.
Of the above hydrogenation catalyst manufacturing methods, in a catalyst formed by the TIE method, pores of the porous material do not collapse in the step of carrying the transition metal, and pores within a predetermined range are regularly arranged. That is, a catalyst formed by this TIE method is preferable in that it can carry a large amount of transition metal while the pore structure of the porous material before the transition metal is loaded is maintained.
A method of manufacturing a hydrogenation product according to the present invention will be described below.
In the presence of the above-mentioned catalyst in which a transition metal is carried by a porous material in which 90% or more of all pores are fine pores each having a diameter of 1 to 50 nm, a gas mixture of hydrogen and carbon monoxide is reacted at a temperature of 200 to 400xc2x0 C. and a pressure of 0.1 to 10 MPa to manufacture a hydrogenation product containing gasoline fuel oil components or diesel fuel oil components.
More specifically, the catalyst in the form of, e.g., a powder is packed into a cylindrical stainless-steel high-pressure reaction tube, and this reaction tube is heated by a heater placed outside the reaction tube such that the internal temperature of the tube is 200 to 400xc2x0 C. In this state, a high-pressure gas mixture (0.1 to 10 MPa) of hydrogen and carbon monoxide is supplied to manufacture a hydrogenation product.
Alternatively, a slurry formed by dispersing the powdery catalyst in a high-boiling organic solvent is placed in a high-pressure tank having an entrance and exit. While this high-pressure tank is heated by a heater placed outside the tank such that the internal temperature of the tank is 200 to 400xc2x0 C., a high-pressure gas mixture (0.1 to 10 MPa) containing hydrogen and carbon monoxide is supplied into the slurry from the entrance. A hydrogenation product can also be manufactured by this method.
The catalyst can be used in the form of a powder (e.g., the average grain size is 50 to 150 xcexcm) or granules formed by pulverizing pellets obtained by molding the powder.
The component ratio of the gas mixture cannot be unconditionally defined because it depends on the type of target component selected in a hydrogenation product.
Generally, the ratio of hydrogen (H2): carbon monoxide (CO) is preferably 1:1 to 4:1. For example, when the component to be selected is a diesel fuel oil component, the mixing ratio of hydrogen (H2): carbon monoxide (CO) in the gas mixture is preferably 2:1.
In a reaction system for reacting the gas mixture in the presence of the catalyst, by setting the temperature and the pressure within the above ranges it is possible to arbitrarily select, as target components, methane C1 to butane C4, gasoline fuel oil components C5 to C9, diesel fuel oil components C10 to C20, and high-boiling paraffin such as wax.
The flow rate when the gas mixture is supplied to the high-pressure reaction tube has influence on the conversion of carbon monoxide. Generally, the lower the flow rate of the gas mixture the higher the conversion of carbon monoxide. However, the distribution of each component of a hydrogenation product manufactured also changes, and this changes the yield of target components. Hence, to increase the yield of target components, i.e., to increase the selectivity, the flow rate of the gas mixture is preferably 50 to 100 cm3/min at 0.1 MPa and 20xc2x0 C.
As described above, a hydrogenation catalyst of carbon monoxide according to the present invention has a structure in which a transition metal is loaded by a porous material in which 90% or more of all pores are fine pores each having a diameter of 1 to 50 nm.
In a catalyst having this structure, pores of the porous material on which the transition metal is loaded are very fine, and the pore distribution is very narrow. Therefore, this catalyst is suited to the manufacture of a hydrogenation product containing target components (e.g., gasoline fuel oil components or diesel fuel oil components) at high selectivity from a gas mixture of hydrogen and carbon monoxide.
In particular, a catalyst formed by the TIE method described previously can hold a large amount of transition metal while the pore structure of a porous material before the transition metal is carried is maintained. Hence, this catalyst is suited to the manufacture of a hydrogenation product containing target components (e.g., gasoline fuel oil components or diesel fuel oil components) at higher selectivity.
Also, by defining the loaded amount of the transition metal (5 to 40 wt % in the case of cobalt, 1 to 15 wt % in the case of ruthenium), during the reaction of a gas mixture of hydrogen and carbon monoxide the conversion of carbon monoxide can be improved. In addition, it is possible to manufacture a hydrogenation product containing target components (e.g., gasoline fuel oil components or diesel fuel oil components) at higher selectivity.
Furthermore, in the method of manufacturing a hydrogenation product according to the present invention, in the presence of the aforesaid catalyst a gas mixture of hydrogen and carbon monoxide is reacted at a temperature of 200 to 400xc2x0 C. and a pressure of 0.1 to 10 MPa.
This method uses the catalyst in which a transition metal is carried by a porous material in which pores are very fine and the pore distribution is very narrow. Therefore, the activating action of the transition metal present in a large number of very fine pores allows easy progress of the reaction from a gas mixture of hydrogen and carbon monoxide to target components, particularly gasoline fuel oil components C5 to C9 and diesel fuel oil components C10 to C20. Consequently, a hydrogenation product containing large amounts of these components can be manufactured.
In particular, when the gas mixture is reacted at a predetermined temperature and a predetermined pressure by using a catalyst formed by the TIE method and carrying a large amount of transition metal while the pore structure of a porous material before the transition metal is carried is maintained, it is possible to manufacture a hydrogenation product containing target components (e.g., gasoline fuel oil components or diesel fuel oil components) at higher selectivity. This is caused by the following behavior.
The selectivity of a hydrogenation product when hydrogen and carbon monoxide react with each other depends upon the carbon chain growth probability. In a catalyst formed by the TIE method, the active sites of a transition metal carried are present inside pores. Therefore, the reaction of the gas mixture progresses primarily inside those pores. This encourages an intermediate product generated by the reaction of the gas mixture to again adsorb on the active sites. So, the carbon chain growth probability efficiently increases. Accordingly, it is possible to manufacture a hydrogenation product containing gasoline fuel oil components C5 to C9 and diesel fuel oil components C10 to C20, each having a large number of carbon atoms, at higher selectivity.